Excavation machine including cutting discs and corresponding cutting method

ABSTRACT

The application relates to an excavation machine including a cutting head with a first drum and a second drum positioned side by side, in proximity to one another, and configured to turn respectively around a first and a second axis of rotation, the first drum and the second drum including, according to their respective axis of rotation, a proximal end connected to the cutting head, and a distal end opposite to the proximal end. The application also relates to a cutting disc for an excavation machine of this type, as well as a corresponding cutting method.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to French Patent application number FR2207608 filed on Jul. 25, 2022. The contents of which are incorporated by reference herein.

TECHNICAL FIELD

The present application has as its object the field of excavation and ground cutting machines, using rotating cutters, allowing in particular the creation of slurry walls in the ground.

BACKGROUND

To create slurry walls of this type, it may be necessary first of all to dig a trench, the geometry of which corresponds to the wall to be created. Then the trench is filled with a grout or a concrete, possibly provided with reinforcements, to obtain the slurry wall.

When the wall has a certain depth and it must be created with great accuracy, excavation machines of the hydromilling cutter type are most often used, in which the cutting head is equipped with two rotating assemblies provided with excavation tools. These tools break up the ground or the rock under the influence of the vertical thrust, which produces large quantities of cuttings. During the drilling operation, the trench is kept filled with drilling fluid. The drilling cuttings present in the drilling fluid are then removed from the trench by pumping.

Referring to appended FIGS. 1 and 2 , an exemplary embodiment of an excavation machine of a known type will be described.

Shown in FIG. 1 is an excavation assembly 9, similar to that described in application FR 2 806 111 which comprises a bearer 10 provided with a boom 12. Lifting cables 16, at the end 18 of which is mounted the actual excavation machine 20, pass over the end 14 of the boom 12. This machine 20 comprises a vertical frame 22, at the lower end of which is mounted a cutting head 24. The cutting head consists essentially of two rotating cutting assemblies 26 and 28 with horizontal axes of rotation, X-X′, parallel to one another. Preferably, each rotating cutting assembly consists of two cutters or drums mounted symmetrically on the frame. The excavation machine can also include a suction port 30, arranged at the lower end of the frame between the two rotating cutting assemblies 26 and 28, to allow cuttings to be brought up, a suction pipe 32 connecting the suction port 30 to a suction device 34, for example a pump, and a pipe 36 which allows aspirating the drilling fluid containing cuttings for the purpose of removing it to a recovery installation. At the surface, another pipe is also provided to fill the trench with the drilling fluid.

In known excavation machines, cylindrical drums rotate inside a volume of mud consisting of the lower portion of two half-cylinders created by the cut produced by the excavation tools mounted on the drums, this volume extending essentially to the lower edge of the frame.

However, excavation machines of this type are not designed to work in any type of ground. Thus, during the digging of certain trenches, the excavation machine can encounter foreign bodies, particularly cables or tie rods, capable of blocking the cutting head by winding around the rotating cutting assemblies, perhaps damaging the cutting head, for example when cutting tie rods under tension.

When foreign bodies of this type are detected, or even previously located prior to the work of the excavation machine, it is then provided to use other machines or systems intended to remove or to neutralize the foreign bodies in question.

Such is the case for example with anchoring cables, or tie rods, which can be present in the ground due to earlier work and remain in place afterward. Cables of this type can complicate digging work by excavation machines which will be led to cut them to be able to dig. In particular, when the cable is to be cut, freeing tension energy initially stored in the cable can occur, and is likely to damage the excavation machine. In addition, the cables can block and perhaps damage the excavation machine, particularly the drums or possibly the suction system, for example by winding around the drums of the cutting head.

In such situations, it is known to slacken and possibly withdraw such cables present in the ground, prior to drilling operations by the excavation machine. However, such operations on the cables can be complicated to carry out, without however guaranteeing the absence of other, unidentified or unlisted, cables in the area.

There exists a real need to be able to manage the presence of foreign bodies, such as cables, in the ground to be excavated, in order to allow normal and safe operation of an excavation machine equipped with rotating drums.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an excavation assembly of known type;

FIG. 2 shows in more detail the cutting head of the excavation machine of FIG. 1 ;

FIG. 3 is a schematic view in perspective of a drum, or cutter, for an excavation machine according to a first embodiment of the application;

FIG. 4 is a schematic view in perspective of a cutting disc for an excavation machine according to the first embodiment; and

FIG. 5 is a schematic view in perspective of a cutting head of an excavation machine according to the first embodiment of the application with cutting discs, or according to a second embodiment.

DISCLOSURE

The present application seeks to solve the different technical problems previously mentioned. In particular, the present application seeks to propose an excavation machine allowing digging a trench in ground which can include foreign bodies. More precisely, the present application seeks to propose an excavation machine capable of cutting cables or tie rods present in the ground during the digging of the trench.

Thus, according to one aspect, an excavation machine is proposed including:

-   -   a vertical frame having a lower end;     -   a cutting head mounted at said lower end of the frame, said         cutting head comprising a first drum and a second drum         positioned side by side, in proximity to one another, and         configured to turn respectively around a first and a second axis         of rotation, the first drum and the second drum including,         according to their respective axis of rotation, a proximal end         connected to the cutting head and a distal end opposite to the         proximal end.

Said first drum includes, at its distal end, a first cutting disc or a first mounting means configured to allow the mounting of a first cutting disc. Said second drum includes, at its distal end, a second cutting disc or a second mounting means configured to allow the mounting of a second cutting disc. Said first and second cutting discs respectively have a diameter greater than or equal to that of said first and second drums.

The first and second cutting discs are positioned substantially in the same plane, or the first and second mounting means are configured to position the first and second cutting discs substantially in the same plane.

Thus, the excavation machine includes two cutting discs, or two cutting disc mounting means, mounted in the same plane and side by side so as to allow, during the rotation of the two drums of the cutting head, cutting possible cables or tie rods present in the ground and crossing the alignment of the trench. More precisely, the excavation machine is designed to cut cables or tie rods when they are positioned between said two cutting discs. The excavation machine can thus neutralize cables or tie rods present in the ground, then carry out the usual ground digging operations, without requiring a machine change. In order to cut the cables of tie rods, it is sufficient to position said cable or tie rod between the two cutting discs, for example by rotating the drums so that their lower ends approach one another, then rotating the two drums, preferably in the opposite direction, until the cable or tie rod is cut.

Preferably, the cutting head also comprises a third drum and a fourth drum positioned side by side, in proximity to one another, and configured to turn respectively around the first and the second axis of rotation, the third drum and the fourth drum including, according to their respective axis of rotation, a proximal end connected to the cutting head, and a distal end opposite to the proximal end.

Said third drum includes at its distal end, a third cutting disc or a third mounting means configured to allow the mounting of a third cutting disc. Said fourth drum includes, at its distal end, a fourth cutting disc or a fourth mounting means configured to allow the mounting of a fourth cutting disc. Said third and fourth cutting disc respectively have a diameter greater than or equal to that of said third and fourth drums.

The third and fourth cutting discs are positioned substantially in the same plane, or the third and fourth mounting means are configured to position the third and fourth cutting discs substantially in the same plane.

Conventionally, excavation machines include two rotating cutting assemblies, each including two drums driven in rotation around the same axis of rotation, generally horizontal, an extending substantially over the entire width of the trench to be dug, on either side of the vertical frame of the excavation machine. Thus, with an excavation machine with four drums, it becomes possible to cut only the part of the cable or the tie rod extending in the volume of the trench to be dug: the cutting discs extend to the distal ends of the drums, i.e. along the end walls, or flanks of the trench, they can cut the cables or tie rods at the interface with the trench so as to allow the complete withdrawal of the portion crossing the trench.

Moreover, the drums being mounted on the same axis of rotation, two by two, the two ends of a cable or tie rod portion can be cut at the same time, because each pair of cutting discs can simultaneously cut each end of the cable or tie rod portion.

Preferably, the excavation machine also comprises at least one suction port attached to the cutting head between the first and second drums, and a suction device connected to the suction port to remove the cuttings excavated by the first and second drums.

The suction port allows extracting the cuttings formed by digging the trench, in particular the excavated soil, but not the portions of cable or of tie rod cut by the cutting discs, from the trench. These cuttings are thus routed outside the trench, by aspiration with the drilling liquid circulating at the cutting head. The suction port is positioned between the two drums so as to facilitate the carriage of the cuttings toward them by said drums when they rotate in the direction shown in FIG. 2 , i.e. when their excavation tools, or teeth, perform a rising movement at the central plane of symmetry of the cutting head.

According to a first embodiment, said first and second drums include said first and second mounting means, and said first and second mounting means each include: a bearing surface for the cutting disc, for example with a circular shape or ring-shaped, and attachment means for the cutting disc, for example tapped holes.

In this first embodiment, the cutting discs are removably mounted on the drums of the cutting head. Thus, the drums include the mounting means on which the cutting discs can be mounted, or not, depending on the presence, or not, of cables of tie rods in the trench to be dug. The mounting means are configured to allow effective and reliable mounting of the cutting discs at the distal end of the drums. To this end, the mounting means can comprise, on the one hand, mounting means, for example tapped holes, allowing tightening in them the attachment screws of the cutting disc on the mounting means; and on the other hand a bearing surface, for example disc- or ring-shaped, on which the cutting disc will be supported. The mounting means are thus designed to facilitate the mounting of the cutting disc, but also the maintenance, in operation, of the cutting disc on the drum.

Preferably, the bearing surface also includes openings configured to allow access to the attachment means of the drum on the cutting head.

The bearing surface is configured to leave one or more manholes, for example openings, allowing access to the proximal end of the drum at which the latter is mounted on the cutting head. The manhole or opening thus allows mounting or disassembling the drum from the cutting head, passing through said manhole.

Preferably, the excavation machine also comprises a first cutting disc mounted on said first drum and a second cutting disc mounted on said second drum.

The application therefore relates to the excavation machine including mounting means and a cutting disc mounted on each of the mounting means.

Preferably, the first and second cutting discs include, on their peripheral rim, a cutting material, preferably tungsten carbide or diamond powder.

The cutting discs are designed to allow effective cutting while guaranteeing high mechanical resistance. To this end, cutting discs are provided with a diameter greater than that of the drums, perhaps greater than that of the drums with teeth: it is then possible to obtain a reduced inter-disc distance, and in particular less than the diameter of the cables or tie rods to be cut. Moreover, the edges of the cutting discs are provided with materials having high mechanical resistance, in particular great hardness. Thus, the cutting discs can comprise tungsten carbide, diamond powder or any other material suited for such use. During their cutting, the direction of rotation of the drums is preferably inverted relative to that used during the digging of the trench, i.e. the periphery of the drums performs a descending movement at the central plane of symmetry of the cutting head. The cables or tie rods are thus subjected to the simultaneous action of the edges of the two cutting discs which, on the one hand, are supported on the cable or tie rod under the influence of gravity, and on the other hand exert a downward stress under the influence of the direction of rotation of the discs. Moreover, such a rotation of the drums allows separating the suction port and the cable or tie rod section that is cut: thus the risks of damage to or of blockage at the suction port of the excavation machine are limited. On the other hand, in the case of a cutting head bereft of a suction port, it is possible to constantly retain the same direction of rotation of the drums, whether during digging phases or during cutting phases.

Preferably, the first and second cutting discs also include first and second gripping means, for example openings configured to cooperate with lifting means, and/or include first and second openings, preferably chamfered, for attachment to the first and second mounting means.

In order to facilitate the manipulation of the cutting discs and limit the risk of injury, particularly during the phases of mounting and disassembly on the mounting means of the drums, the cutting discs can include gripping means, for example openings, for coopering with the lifting means, for example hooks. Likewise, cutting discs can also include chamfered openings for their attachment to the mounting means using screws. In particular, the chamfers allow protecting the screw heads during the use of the cutting discs in the trench.

Preferably, the first and second cutting discs are positioned substantially in the same plane with a radial spacing less than or equal to 30 mm, preferably less than or equal to 10 mm, and more preferably less than or equal to 5 mm.

The space between the two discs mounted on two drums side by side, or adjacent, is selected small to obtain cutting of the cable or tie rod that is as complete as possible, the free space between the two adjacent discs defining the residual size of the cable or tie rod able to pass between the two cutting discs.

According to another aspect, a cutting disc configured to be mounted on the mounting means of a drum of an excavation machine including said first and second mounting means, as previously described, is also proposed.

The application also relates to the cutting disc as such, intended to be mounted on the drum of an excavation machine for the purpose of cutting foreign bodies present in the ground to be dug.

According to a second embodiment, said first and second drums include said first and second cutting discs, and the first and second cutting discs include, on their peripheral rim, a cutting material, preferably tungsten carbide or diamond powder and/or openings configured to allow access to the attachment means of the drum on the cutting head.

In this second embodiment, the drums include the cutting discs directly at their distal end: the cutting discs are not mounted and disassembled on the drums depending on the needs of the construction site, but it is the drums provided with cutting discs, or the cutting heads with drums of this type, which are mounted or disassembled on the excavation machine depending on the needs of the construction site.

Preferably, the first and second cutting discs are positioned substantially in the same plane with a radial spacing less than or equal to 30 mm, preferably less than or equal to 10 mm, and more preferably less than or equal to 5 mm.

As for the first embodiment, the distance between the cutting discs of the excavation machine according to the second embodiment is selected small, to cut a maximum section of cable or tie rod, and limit the residual size of those which could pass between the two cutting discs.

According to another aspect, a method for cutting a metal element, for example a cable, is also proposed, with an excavation machine according to the first embodiment with cutting discs mounted on the mounting means, or according to the second embodiment in which the drums are rotated in opposite direction, with their lower ends moving away from or approaching one another, and the cutting head is translated downward when it is positioned above the metal element to be cut.

As indicated previously, the direction of rotation of the drums can be selected to that their lower ends move away from one another. Such a direction of rotation can in particular be opposite to that used during the digging of the trench. Thus, during digging, the drums turn so as to route the cuttings between the two drums, where the suction port allows removing said cuttings with the drilling fluid, while during cutting, the drums route the cuttings, and in particular the sections of cables or of tie rods, away from the suction port. It should also be noted that, prior to cutting, in particular when the cables or tie rods are not initially positioned on the axis of the interval separating the two drums, the drums can be rotated with their ends approaching one another, so as to position said cables or tie rods located in said interval separating the two drums, then, during the cutting phase, the drums can be rotated in the opposite direction of rotation to perform the cutting. Moreover, in order to improve the cutting effect of the rim of the cutting discs, the excavation machine also uses the weight of the cutting head to hold the cutting discs in contact with the cable or the tie rod during the cutting operation.

Alternatively, the direction of rotation of the drums, during the phase of cutting the metal element, can be selected so that their lower ends approach one another. Such a direction of rotation corresponds in particular to that used during the digging of the trench. Such a direction of rotation can in particular be used during the phase of cutting the metal element, when the cutting head is bereft of a suction port: in such a case, there is no risk that the portion of the cut metal element is blocked in or damages the port or the suction system. The direction of rotation of the drums can then remain the same, whether during the phases of digging the trench or during the phases of cutting a metal element.

Thus when the excavation machine according to the present application is bereft of a suction port, the rotation of the drums can always occur in the same direction, with the lower ends approaching one another, or in different direction during the digging phases and during the cutting phases. More precisely, during the digging phase, the drums can turn so that their lower ends approach one another, so as in particular to position the cables or tie rods in the interval separating the two drums, then, during the cutting phase, the drums can be driven in rotation in the same direction, or in the opposite direction, with their lower ends moving away from one another.

Preferably, with an excavation machine according to the first embodiment, the first and second cutting discs are attached, possibly after having removed the teeth from the drums, to the first and second mounting means of two drums of the excavation machine, the first and second cutting discs extending substantially in the same plane.

Within the scope of the first embodiment, the cutting discs are mounted on the mounting means prior to the cutting operations. In this case, it is in fact necessary to extract the excavation machine from the trench so as to mount the cutting discs on it, but it is not necessary to use another distinct machine to cut the tie rods or cables: the excavation machine can remain on-site and carry out successively the steps of digging, cutting, then again digging, which limits the operations to be carried out by the operators and therefore the time necessary to carry them out.

Finally, the teeth can be removed beforehand from the drums, in particular in order to avoid that the cut section of cable or tie rod winds on it or blocks it.

Preferably, with an excavation machine according to the second embodiment, the drums including the first and second cutting discs, or the cutting head including said drums, are attached to the excavation machine, the first and second cutting discs extending substantially in the same plane.

Within the scope of the second embodiment, the drums with the cutting disc, or the corresponding cutting head, are mounted on the excavation machine prior to the cutting operations. In this case, it is actually necessary to extract the excavation machine from the trench in order to mount on it the drums with cutting discs, or the corresponding cutting head, but it is not necessary to use another distinct machine to cut the tie rods or cables: the excavation machine can remain on-site and carry out successively the steps of digging, cutting, then again digging, which limits the operations to be carried out by the operators and therefore the time necessary for carrying them out.

Preferably, drums including a cutting disc can be bereft of teeth.

DESCRIPTION OF THE EMBODIMENTS

FIGS. 3 and 4 show an example of a drum 40 and an example of a cutting disc 50 for an excavation machine according to the first embodiment of the application.

The drum 40 includes, conventionally, a proximal end 42 extending substantially in a plane perpendicular to the axis of rotation of the drum 40, and a distal end 44 opposite to the proximal end 42 and extending substantially in a plane parallel to that of the proximal end. The proximal 42 and distal 44 ends delimit substantially the width of the drum 40 in the direction of its axis of rotation. Thus, the axis of rotation of the drum 40 being intended to be substantially horizontal in operation, the proximal 42 and distal 44 ends extend substantially vertically when the drum 40 is mounted and used on the cutting head 24.

In order to allow mounting and driving in rotation of the drum 40, the cutting head 24 includes cooperation means (not shown) on which is mounted the drum 40. More precisely the drum 40 is mounted on the cutting head 24 by its proximal end 42, while the distal end 44 extends opposite to the cutting head 24.

Moreover, the drum 40 also includes, along its periphery, excavation tools, for example teeth 46 mounted on gussets 48 provided with tooth carriers, driven in rotation by the drum 40 and allowing the ground to be dug during excavation. The teeth 46 and the gussets 48 can extend in different digging planes which are, for example perpendicular to the axis of rotation of the drum 40 and which are distributed over the width of the drum 40. Thus, in FIG. 3 , the gussets 48 and the teeth 46 are positioned in two parallel planes arranged respectively in proximity to the proximal 42 and distal 44 ends of the drum 40. The gussets 48 and the teeth 46 can form a ring extending all along the periphery of the drum 40, or form only segments partially surrounding the drum 40. Such segments are then defined directly by the different gussets 48. In particular, the positions of the different segments formed by the gussets 48 on the rim of the drum 40 can be selected alternating between the different digging planes, possibly with overlap between the different alternating segments.

The teeth 46 of the distal end 44 thus allow digging at the lateral wall of the trench created by the excavation machine, while the teeth located at the proximal end 42 or between the proximal end 42 and the distal end 44 allow digging inside the trench created by the excavation machine.

However, during the digging of certain trenches, the excavation machine can encounter foreign bodies, particularly cables or tie rods, likely to block the cutting head 24 by winding around the rotating cutting assemblies, perhaps damaging the cutting head 24, for example when cutting tie rods under tension.

Thus, in order to neutralize such foreign bodies and continue the excavation of the trench, the excavation machine 20 according to the present application can comprise two or more cutting discs 50 as shown in FIG. 4 .

According to the first embodiment illustrated in FIG. 3 , the drum 40 can includes mounting means 52 intended to allow the mounting of a cutting disc at the distal end 44 of the drum 40. The mounting means 52 can in particular comprise, on the one hand, attachment means 54 allowing the attachment of the cutting disc 50 to the distal end 44 of the drum 40. The attachment means 54 can for example be tapped holes intended to cooperate with attachment screws of the cutting disc 50.

In particular, the mounting means 52, and more particularly the attachment means 54, are configured to allow reversible mounting of the cutting disc 50 on the drum 40, i.e. the cutting disc 50 is removable. An embodiment of this type thus allows using the cutting head 24 of the excavation machine 20 conventionally during excavation work, and improving it with cutting discs 50 when foreign bodies, particularly cables or tie rods, are present in the area to be excavated.

Moreover, the mounting means 52 can also include a bearing surface 56. The bearing surface 56 is intended to form a stable support for the cutting disc 50, allowing taking up the possible forces or stresses which may be exerted on the interface between the drum 40 and the cutting disc 50 during the operation of the cutting head 24. The bearing surface 56 is mounted at the distal end 44 of the drum 40 and has an exposed surface intended to come into contact with the cutting disc 50 when it is mounted on the drum 40.

In the case illustrated in FIG. 3 , the bearing surface 56 has the general shape of a ring, and has an exposed surface area, for contact with the cutting disc 50, that is greater than the transverse section of a drum bereft of such a bearing surface. The bearing surface 56 is secured to the drum 40, is welded for example to the transverse section of the drum 40.

The ring shape of the bearing surface 56 allows retaining free access to the interior volume of the drum 40 all around the axis of rotation. However, such a bearing surface 56 could limit access to the attachment means of the drum 40 on the cutting head 24 (at the proximal end 42 of the drum 40). Thus, the bearing surface 56 can comprise openings 58, six in number in the present case, distributed over the rim of the bearing surface and giving access to the attachment means of the drum 40 on the cutting head 24. Thus, to attach or withdraw the drum 40 from the cutting head 24, it is sufficient to withdraw the cutting disc 50 from the attachment means 52, then gain access to the attachment means of the drum 40 via the openings 58.

The drum 40 according to the first embodiment therefore has a very similar geometry and use to those of traditional drums, with the exception of the mounting means 52 provided at the distal end 44 of the drum 40 and configured to allow the mounting of a cutting disc 50 at the distal end 44 of the drum 40. In particular, in the absence of foreign bodies in the trench to be excavated, the attachment/withdrawal operations of the drum on the cutting head, and the operations of digging the trench remain identical to those implemented with traditional drums.

FIG. 4 illustrates an example of the cutting disc 50. The cutting disc 50 illustrated in FIG. 4 is a removable cutting disc 50 used with a drum 40 according to the first embodiment.

The cutting disc 50 preferably has the general shape of a ring, i.e. a disc shape with a central hole. The central hole is intended to leave free access to the interior volume of the drum 40 on which it is mounted, all around the axis of rotation of said drum 40.

In order to mount the cutting disc 50 on the drum 40, the cutting disc 50 can include chamfered openings 60 in which attachment screws (not shown) can be mounted then screwed into the attachment means 54 of the drum 40. The chamfer allows in particular, during the use of the cutting discs 50 during the excavation operations, to avoid wearing, perhaps breaking, the screw heads by friction on the wall of the trench in the course of excavation.

Moreover, in order to facilitate the handling of the cutting disc 50 during its attachment or its withdrawal from the drum 40, gripping means 62, for example in the form of openings allowing a lifting hook to be inserted into it, are provided, preferably in proximity to the peripheral rim of the cutting disc 50.

Finally, the cutting disc 50 advantageously includes a cutting material 64 over all or part of its rim. The cutting disc 50 being intended to cut foreign bodies present in the ground, particularly cables or tie rods, the purpose of the cutting material is, on the one hand, to obtain more rapid cutting of the foreign body, and on the other hand to limit the wear of the peripheral rim of the cutting disc 50. To this end, the cutting material is advantageously selected among materials having high hardness, for example diamond dust, tungsten carbide or other material suitable for such use.

FIG. 5 illustrates a cutting head 24 with cutting discs according to the first embodiment. In particular, the cutting head 24 comprises drums, for example four drums 40′, 40″, 40′, 40″″ mounted in pairs on the two horizontal axes of rotation X-X′, and cutting discs, for example four cutting discs 50′, 50″, 50′, 50″″ associated respectively with each of the four drums 40′, 40″, 40″, 40″″.

In the first embodiment, each drum 40′, 40″, 40″, 40″″ of the excavation machine corresponds to the drum 40 illustrated in FIG. 3 , and each cutting disc 50′, 50″, 50″, 50″″ corresponds to the cutting disc 50 illustrated in FIG. 4 .

As can be observed, the cutting discs are arranged by pairs, in two parallel planes. Thus, the first and second cutting discs 50′ and 50″ are positioned substantially in the same plane, which corresponds to the plane of the distal ends 44′, 44″ of the first and second drums 40′, 40″, while the third and fourth cutting discs 50″ and 50″″ are positioned substantially in the same plane, which corresponds to the plane of the distal ends 44′″, 44″″ of the third and fourth drums 40′″, 40″″.

Thus associated, each pair of cutting discs allows cutting foreign elements, particularly cables or tie rods, crossing the trench to be excavated through at least one of its lateral walls. In this case, the cutting head 24 is placed in the trench so as to position said foreign body between the both cutting discs of the same plane. The movement of each cutting disc thus allows cutting said foreign body by two opposite sides until a complete cut is obtained.

In order to obtain a rapid and total cut, the cutting discs of the same pair (i.e. positioned in the same plane) are near to one another, for example separated by a distance less than 30 mm, preferably less than 10 mm and more preferably less than 5 mm.

According to a second embodiment, each drum 40′, 40″, 40′″, 40″″ includes, at its distal end, a cutting disc 50′, 50″, 50′″, 50″″ secured to said drum.

In this case, the cutting disc is no longer removable, and no longer includes attachment openings 60. The drum no longer comprises mounting means 52. On the other hand, openings for access to the attachment means of the drum on the cutting head can be provided in the cutting disc.

During the implementation of the excavation machine for cutting the foreign body, particularly the cable or the tie rod, the cutting head 24 is configured to allow rotation of the drums, and thus of the corresponding cutting discs, in the direction opposite to that used during the digging of the trench. More precisely, the cutting head 24 is configured to turn the drums so that, at the narrowest point between the two cutting discs, the peripheral rim descends, i.e. in such a manner that the lower ends of the cutting discs turn while moving away from one another. Such a movement corresponds to a clockwise direction of rotation for the first cutting disc 50′ and a counter-clockwise direction of rotation for the second cutting disc 50″.

At the same time, the cutting head 24 can be translated downward, i.e. toward the foreign body, or can simply exert pressure on the foreign body under the influence of its own weight. The contact force between the foreign body and the cutting material of the cutting discs is thus increased, which allows improving the effect of wear or of cutting of the cutting material on the foreign body.

However, before turning the drums as previously described to perform the cutting, it is possible to turn them in the opposite direction so as to naturally position the foreign body in the interval separating the two discs, in particular when the foreign body is not initially positioned in the axis of said interval. Once the foreign body is positioned between the two cutting discs, the drums can then be rotated in the other direction so as to carry out the cutting of the foreign body.

In the case of a cutting head bereft of a suction port, the drums can be rotated, during the cutting phase of the foreign body, in the same direction as during the digging phase, i.e. with the lower end of the cutting discs approaching one another. In this case, the direction of rotation of the drums remains the same during the entire duration of operation of the cutting head.

In addition, and prior to the cutting of the foreign body, it is also possible to provide withdrawal of the teeth 46 from the drums 40 of the cutting head 24. In fact, and even if the cutting discs extend radially beyond the teeth 46, the foreign body to be cut could nevertheless be entrained by the teeth 46 and damage, perhaps block the drum 40 by winding itself around it. In order to limit such a risk, the teeth 46 can be removed from the gussets 48 prior to cutting.

Thus, due to the drum and to the cutting disc according to the present application, it becomes possible to dig a trench including foreign bodies in a safer and more rapid manner. Indeed the cutting discs allow in situ and rapid cutting of foreign bodies present in the trench without requiring the use of another machine and while limiting the risks of deterioration of the equipment that is used. In particular, the drums according to the present application take advantage of the operation of the cutting head to allow effective and complete cutting of possible cables or tie rods extending through the trench. 

1. An excavation machine including: a vertical frame having a lower end; a cutting head mounted at said lower end of the frame, said cutting head comprising a first drum and a second drum positioned side by side, in proximity to one another, and configured to turn respectively around a first and a second axis of rotation, the first drum and the second drum including, according to their respective axis of rotation, a proximal end connected to the cutting head, and a distal end opposite to the proximal end, wherein: said first drum includes, at its distal end, a first cutting disc or a first mounting means configured to allow mounting a first cutting disc, said second drum includes, at its distal end, a second cutting disc or a second mounting means configured to allow mounting a second cutting disc, wherein said first and second cutting discs respectively have a diameter greater than or equal to that of said first and second drums, and wherein the first and second cutting discs are positioned in the same plane, or the first and second mounting means are configured to position the first and second cutting discs in the same plane.
 2. The excavation machine according to claim 1, wherein said first and second drums include said first and second mounting means, and wherein each of said first and second mounting means include: a bearing surface for the cutting disc, and fasteners configured to attach the cutting disc.
 3. The excavation machine according to claim 2, wherein the bearing surface also includes openings configured to allow access to the fasteners of the drum on the cutting head.
 4. The excavation machine according to claim 1, wherein said first and second drums include said first and second mounting means, and wherein the excavation machine also comprises a first cutting disc mounted on said first drum and a second cutting disc mounted on said second drum.
 5. The excavation machine according to claim 4, wherein the first and second cutting discs include, on their peripheral rim, a cutting material.
 6. The excavation machine according to claim 4, wherein the first and second cutting discs also include first and second openings configured to cooperate with a lifter, and or include first and second openings for attachment to the first and second mounting means.
 7. The excavation machine according to claim 1, wherein said first and second drums include said first and second cutting discs, and wherein the first and second cutting discs include, on their peripheral rim, a cutting material and/or openings configured to allow access to the fasteners of the drum on the cutting head.
 8. The excavation machine according to claim 1, wherein: said first and second drums include said first and second cutting discs, and the first and second cutting discs are positioned in the same plane with a radial spacing less than or equal to 30 mm.
 9. The excavation machine according to claim 1, wherein: said first and second drums include said first and second mounting means, and the first and second mounting means are configured to position the first and second cutting discs in the same plane with a radial spacing less than or equal to 30 mm.
 10. The excavation machine according to claim 1, wherein the cutting head further comprises a third drum and a fourth drum positioned side by side, in proximity to one another and configured to turn respectively around the first and the second axes of rotation, the third drum and the fourth drum including, according to their respective axis of rotation, a proximal end connected to the cutting head, and a distal end opposite to the proximal end; wherein: said third drum includes, at its distal end, a third cutting disc or a third mounting means configured to allow the mounting of a third cutting disc, said fourth drum includes, at its distal end, a fourth cutting disc or a fourth mounting means configured to allow the mounting of a fourth cutting disc, wherein said third and fourth cutting discs respectively have a diameter greater than or equal to that of said third and fourth drums, and wherein the third and fourth cutting discs are positioned in the same plane, or the third and fourth mounting means are configured to position the third and fourth cutting discs in the same plane.
 11. The excavation machine according to claim 1, also comprising at least one suction port attached to the cutting head between the first and second drums, and a suction device connected to the suction port for removing cuttings excavated by the first and second drums.
 12. The excavation machine according to claim 5, wherein the cutting material is tungsten carbide.
 13. The excavation machine according to claim 5, wherein the cutting material is diamond powder.
 14. The excavation machine according to claim 7, wherein the cutting material is tungsten carbide.
 15. The excavation machine according to claim 7, wherein the cutting material is diamond powder.
 16. A cutting disc configured to be mounted on a first drum of a cutting head of an excavation machine, wherein the cutting disc has a diameter greater than or equal to that of the first drum, wherein the cutting disc is configured to be positioned in the same plane as a second cutting disc mounted on a second drum of the cutting head.
 17. A method for cutting a metal element with an excavation machine having a cutting head comprising a first drum and a second drum positioned side by side, the method comprising: rotating the first drum and the second drum in opposite directions, with their lower ends moving away from or approaching one another, wherein the cutting head is translated downward when it is positioned above the metal element.
 18. The method of claim 17, wherein first and second cutting discs are attached, after having removed teeth from the first drum and the second drum, to the first drum and the second drum of the excavation machine, the first and second cutting discs extending in the same plane.
 19. The method of claim 17, wherein first and second cutting discs are attached, after having removed teeth from the first drum and the second drum, to the first drum and the second drum of the excavation machine, the first and second cutting discs extending in the same plane.
 20. The method of claim 19, wherein the first and second cutting discs are attached to the first drum and the second drum via a bearing surface and tapped holes. 